PQQGDH is glucose dehydrogenase (GDH) using pyrroloquinoline quinone as a coenzyme, and can be used for assay of blood glucose because it catalyzes a reaction in which glucose is oxidized to produce gluconolactone. A glucose concentration in blood is a very important indicator as an important marker for diabetes in clinical diagnosis. Although measurement of blood glucose concentration is currently mainly performed by methods using a biosensor that uses glucose oxidase, since the reaction is affected by dissolved oxygen concentration, there was the possibility of the occurrence of error in the measured values. PQQ dependent glucose dehydrogenase has attracted attention as a new alternative enzyme to glucose oxidase.
Our group found that Acinetobacter baumannii strain NCIMB11517 produces PQQGDH, and constructed a gene cloning and high expression system (see, for example, Japanese Patent Application Laid-open No. H11-243949). However, this wild type of PQQGDH had problems with activity with respect to sugar other than glucose (i.e., substrate specificity), and with respect to maltose in particular, as compared with glucose oxidase.